The doping of polymers to obtain semiconductor bodies is known. Either compounds that confer a positive charge (P doping) or compounds that confer a negative charge (N doping) to the polymers are used.
Numerous patents and publications describe the P doping of polymers by electron-acceptor compounds such as iodine or arsenic pentafluoride (Japanese Patent No. 81 145 929 deposited by Showa Denko), strong acids (Japanese Patent No. 80 129 425 of Showa Denko), or titanium salts (U.S. Pat. No. 4,349,664 of Japan Synthetic Rubber Co.).
N doping has not yet been extensively studied. A few publications refer to N doping by electrochemical means or by addition of electron-donor compounds to the polymers. As electron donors, alkali metals, alone, mixed or amalgamated, and alkali salts of radical-ions (European Patent 54683 of BASF) have been suggested.
Doping with alkali metals requires a metal/solid reaction which is difficult to control.
The synthesis of alkali salts of radical-ions such as sodium naphthalyde or the alkali metal complexes of aromatic ketones requires the presence of a polar solvent. If the metal used is sodium or lithium, the solvent also enters into the polymer and exerts a deleterious effect on the conductivity of the polymer. The insertion of the solvent into the polymer increases the weight of the polymer, which defeats some of the objectives sought in using them.
The invention provides a method for doping of polyacetylene and polyphenylene by a process that is simple and effective. The process makes it possible to obtain polymers with good conductivities both in polar and in non-polar solvents.